Can you grow
an organ in the lab? Can you grow new cells to replace diseased
ones? Embryonic stem (ES) cells have the potential to grow into any
cell in the body, but how is the cell type determined? These are
questions a Café Scientifique event at The Royal
Society promised to
explore.

This free event was part of The Royal Society's Summer Science Exhibition, an annual display of
some of the UK's cutting-edge science and technology, and was led by Dr Kevin Chalut, a Royal Society research fellow from the University of Cambridge.

Dr Chalut began
by asking the audience 'what is a stem cell and how can it be defined?' In
reply, most scientists would recite the classic line that 'a stem cell
comprises a self-renewing and dividing population whose function is to maintain
healthy tissue'. However, Dr Chalut considers this definition unsatisfactory,
and I now agree with him. We are defining stem cells by what they are doing,
not what they are. He likened this to defining a hat as 'something you put on
your head!'

Not having a
decent definition for what stem cells are could cause considerable problems. Much
work in the stem cell field is about reprogramming adult stem cells into an ES-like state. However, to quote Dr Chalut, 'we can't make them into a "thing"
if we don't know what that "thing" is'.

The talk
continued with an overview of how malfunctioning stem cells might actually lie
at the root of some diseases. For example, in multiple sclerosis, stem cells should be able to replenish
the cells that perish (oligodendrocytes) but something goes wrong and they are
unable to do so. Conversely, in some cancers stem cells
can divide in an unchecked and uncontrolled manner, resulting in tumour
formation.

Dr Chalut then
focused on his own lab's research. He believes that in order to understand stem
cells and the diseases they cause, we need to understand the environment the
stem cell is found in as much as the stem cell itself.

His team of
researchers are trying to understand the physical interplay between stem cells
and their environment. Stem cells respond to physical as well as biochemical
cues and by providing the correct stimuli researchers hope to better control
what stem cells differentiate into.

A question and
answer session with the audience followed. Many of the questions were about
potential clinical applications: 'has
there been any practical medical success with stem cells?', 'how well do injected
stem cells re-integrate into an organ?' and 'can we use our knowledge of stem
cells to slow down the ageing process?'

Dr Chalut pointed
out that he wasn't a clinician but still gave some intriguing answers. He discussed
several recent medical accomplishments including the regeneration of organs, at
least in part, using stem cells and the ability to make cells taken from human fetuses grow into functional kidneys in a
mouse.

However,
despite the advances that these two men in particular have made, Dr Chalut explained
that further insight into the physical and biochemical cues controlling stem
cells is still necessary. The process of re-programming adult cells needs to be
more efficient, he said. If you try and reprogram one million adult stem cells
only about 300 will revert into an ES-like state and these cells often don't
stay there for very long. For instance, a neuron which has been
reprogrammed into an ES cell-like cell will often wander back into a neuron-resembling cell type.

On a more
personal level, when asked how he began researching stem cell development, Dr
Chalut revealed that although he obtained a doctorate in accelerator physics he
was drawn towards stem cell biology as he considers the problems in biology to
be more important than those in physics!

Overall it was an engaging evening. I would
definitely recommend joining scientists and other specialists to explore
current issues in science over a drink at Café Scientifique.

We live in a world in which the demand for progress and solutions is at fever pitch. But by overlooking projects that may not yield immediate benefits, or ignoring the fundamental science that can unexpectedly make new discoveries, we risk missing out on invaluable new understandings, technologies and treatments...

I'd not been to a Cafe Scientifique event before and was a little unsure of what to expect. The Royal Brompton coffee shop setting did at first feel strange; I'm more used to discussions in lecture theatres where there is a clear distinction between audience and speaker...